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  <div class="section" id="mapping-protocol">
<span id="mapping"></span><h1>映射协议<a class="headerlink" href="#mapping-protocol" title="永久链接至标题">¶</a></h1>
<p>参见 <a class="reference internal" href="object.html#c.PyObject_GetItem" title="PyObject_GetItem"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyObject_GetItem()</span></code></a>、<a class="reference internal" href="object.html#c.PyObject_SetItem" title="PyObject_SetItem"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyObject_SetItem()</span></code></a> 与 <a class="reference internal" href="object.html#c.PyObject_DelItem" title="PyObject_DelItem"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyObject_DelItem()</span></code></a>。</p>
<dl class="function">
<dt id="c.PyMapping_Check">
int <code class="sig-name descname">PyMapping_Check</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *o</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMapping_Check" title="永久链接至目标">¶</a></dt>
<dd><p>如果对象提供映射协议或支持切片则返回 <code class="docutils literal notranslate"><span class="pre">1</span></code>，否则返回 <code class="docutils literal notranslate"><span class="pre">0</span></code>。 请注意它将为具有 <a class="reference internal" href="../reference/datamodel.html#object.__getitem__" title="object.__getitem__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__getitem__()</span></code></a> 方法的 Python 类返回 <code class="docutils literal notranslate"><span class="pre">1</span></code>，因为在一般情况下无法确定它所支持的键类型。 此函数总是会成功执行。</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMapping_Size">
Py_ssize_t <code class="sig-name descname">PyMapping_Size</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *o</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMapping_Size" title="永久链接至目标">¶</a></dt>
<dt id="c.PyMapping_Length">
Py_ssize_t <code class="sig-name descname">PyMapping_Length</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *o</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMapping_Length" title="永久链接至目标">¶</a></dt>
<dd><p id="index-0">成功时返回对象 <em>o</em> 中键的数量，失败时返回 <code class="docutils literal notranslate"><span class="pre">-1</span></code>。 这相当于 Python 表达式 <code class="docutils literal notranslate"><span class="pre">len(o)</span></code>。</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMapping_GetItemString">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="sig-name descname">PyMapping_GetItemString</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *o</em>, const char<em> *key</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMapping_GetItemString" title="永久链接至目标">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p>返回 <em>o</em> 中对应于字符串 <em>key</em> 的元素，或者失败时返回 <code class="docutils literal notranslate"><span class="pre">NULL</span></code>。 这相当于 Python 表达式 <code class="docutils literal notranslate"><span class="pre">o[key]</span></code>。 另请参见 also <a class="reference internal" href="object.html#c.PyObject_GetItem" title="PyObject_GetItem"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyObject_GetItem()</span></code></a>。</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMapping_SetItemString">
int <code class="sig-name descname">PyMapping_SetItemString</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *o</em>, const char<em> *key</em>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *v</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMapping_SetItemString" title="永久链接至目标">¶</a></dt>
<dd><p>在对象 <em>o</em> 中将字符串 <em>key</em> 映射到值 <em>v</em>。 失败时返回 <code class="docutils literal notranslate"><span class="pre">-1</span></code>。 这相当于 Python 语句 <code class="docutils literal notranslate"><span class="pre">o[key]</span> <span class="pre">=</span> <span class="pre">v</span></code>。 另请参见 <a class="reference internal" href="object.html#c.PyObject_SetItem" title="PyObject_SetItem"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyObject_SetItem()</span></code></a>。</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMapping_DelItem">
int <code class="sig-name descname">PyMapping_DelItem</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *o</em>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *key</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMapping_DelItem" title="永久链接至目标">¶</a></dt>
<dd><p>从对象 <em>o</em> 中移除对象 <em>key</em> 的映射。 失败时返回 <code class="docutils literal notranslate"><span class="pre">-1</span></code>。 这相当于 Python 语句 <code class="docutils literal notranslate"><span class="pre">del</span> <span class="pre">o[key]</span></code>。 这是 <a class="reference internal" href="object.html#c.PyObject_DelItem" title="PyObject_DelItem"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyObject_DelItem()</span></code></a> 的一个别名。</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMapping_DelItemString">
int <code class="sig-name descname">PyMapping_DelItemString</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *o</em>, const char<em> *key</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMapping_DelItemString" title="永久链接至目标">¶</a></dt>
<dd><p>从对象 <em>o</em> 中移除字符串 <em>key</em> 的映射。 失败时返回 <code class="docutils literal notranslate"><span class="pre">-1</span></code>。 这相当于 Python 语句 <code class="docutils literal notranslate"><span class="pre">del</span> <span class="pre">o[key]</span></code>。</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMapping_HasKey">
int <code class="sig-name descname">PyMapping_HasKey</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *o</em>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *key</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMapping_HasKey" title="永久链接至目标">¶</a></dt>
<dd><p>如果映射对象具有键 <em>key</em> 则返回 <code class="docutils literal notranslate"><span class="pre">1</span></code>，否则返回 <code class="docutils literal notranslate"><span class="pre">0</span></code>。 这相当于 Python 表达式 <code class="docutils literal notranslate"><span class="pre">key</span> <span class="pre">in</span> <span class="pre">o</span></code>。 此函数总是会成功执行。</p>
<p>请注意在调用 <a class="reference internal" href="../reference/datamodel.html#object.__getitem__" title="object.__getitem__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__getitem__()</span></code></a> 方法期间发生的异常将会被屏蔽。 要获取错误报告请改用 <a class="reference internal" href="object.html#c.PyObject_GetItem" title="PyObject_GetItem"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyObject_GetItem()</span></code></a>。</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMapping_HasKeyString">
int <code class="sig-name descname">PyMapping_HasKeyString</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *o</em>, const char<em> *key</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMapping_HasKeyString" title="永久链接至目标">¶</a></dt>
<dd><p>如果映射对象具有键 <em>key</em> 则返回 <code class="docutils literal notranslate"><span class="pre">1</span></code>，否则返回 <code class="docutils literal notranslate"><span class="pre">0</span></code>。 这相当于 Python 表达式 <code class="docutils literal notranslate"><span class="pre">key</span> <span class="pre">in</span> <span class="pre">o</span></code>。 此函数总是会成功执行。</p>
<p>请注意在调用 <a class="reference internal" href="../reference/datamodel.html#object.__getitem__" title="object.__getitem__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__getitem__()</span></code></a> 方法期间发生的异常将会被屏蔽。 要获取错误报告请改用 <a class="reference internal" href="#c.PyMapping_GetItemString" title="PyMapping_GetItemString"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyMapping_GetItemString()</span></code></a>。</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMapping_Keys">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="sig-name descname">PyMapping_Keys</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *o</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMapping_Keys" title="永久链接至目标">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p>成功时，返回对象 <em>o</em> 中的键的列表。 失败时，返回 <code class="docutils literal notranslate"><span class="pre">NULL</span></code>。</p>
<div class="versionchanged">
<p><span class="versionmodified changed">在 3.7 版更改: </span>在之前版本中，此函数返回一个列表或元组。</p>
</div>
</dd></dl>

<dl class="function">
<dt id="c.PyMapping_Values">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="sig-name descname">PyMapping_Values</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *o</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMapping_Values" title="永久链接至目标">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p>成功时，返回对象 <em>o</em> 中的值的列表。 失败时，返回 <code class="docutils literal notranslate"><span class="pre">NULL</span></code>。</p>
<div class="versionchanged">
<p><span class="versionmodified changed">在 3.7 版更改: </span>在之前版本中，此函数返回一个列表或元组。</p>
</div>
</dd></dl>

<dl class="function">
<dt id="c.PyMapping_Items">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="sig-name descname">PyMapping_Items</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *o</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMapping_Items" title="永久链接至目标">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p>成功时，返回对象 <em>o</em> 中条目的列表，其中每个条目是一个包含键值对的元组。 失败时，返回 <code class="docutils literal notranslate"><span class="pre">NULL</span></code>。</p>
<div class="versionchanged">
<p><span class="versionmodified changed">在 3.7 版更改: </span>在之前版本中，此函数返回一个列表或元组。</p>
</div>
</dd></dl>

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